Will a 455 slip right into the mounts from the old 307?

 

You bet your *** they will. Bolt some 307 motor mounts to the 455 block, and you're good to go.
Big block headers for 73-76 cutlass will bolt in too if you remove the front frame braces. you will have to dimple them 1/4'' by the lower control arms and grind off the bottom firewall lip.

 

Thanks man. I would also like to know what I have to do to the crossmember to put a 350 or a 400 tranny behind it.

 

If you have a 200c metric transmission without overdrive, a short tailed th350 is a direct swap. You will just have to add a metal vacuum line for the modulator.

 

Also, I noticed that your sig says you have a royale, and not a royale brougham.
If your car is a 2 door royale, there were only 15,002 made in 85'.
The 2door royale broughams were 31,891.
4dr royale--69641
4dr royale brougham--102,342

If you have the overdrive trans, you will have to get the crossmember from a 200c car to use with the th350

if you want to use a th400, you will need driveshaft modifications. Th400 uses 32 splines, instead of 27

 

Yes, it happens to be a 2 door coupe and it has the 200c w/ overdrive.
Is there any way to get around getting a new crossmember?
And actually this car is one of the first built in 85.

 

200c does not have overdrive.

2004R is the overdrive trans.


If you have the 2004R, you will need to go get a different X member from a non overdrive 80-85 Lesabre, or Delta 88.

 

Ok I will see if i can find one. Oh I cant wait until i get the new engine and tranny.

 

You might also consider building the 200 4R you have. It will bolt up to your 455 but will tank the first time you step on it unless you build it.

 

Or, you can use the crossmember you have with a TH400. The mount location for a short tailshaft TH400 is in the same location as on the 200-4R. You will need a shortened driveshaft with the correct front yoke.

 

thats some good info!